Episode 31 Engineered Wood Structures with John van de Lindt
Today our host Dan Zehner talks with renowned earthquake engineer John van de Lindt, who has spent the past 20 years exploring wood-structure engineering and community resilience. Van de Lindt also is active in the NHERI hazards engineering community. \xa0 As an undergraduate, he started as a physics major, then moved to criminal justice and considered becoming a lawyer. Fortunately for the engineering world, he was inspired by a Statics course professor and changed his major to structural engineering \u2013 and went on to earn a graduate degree. Ultimately, he appreciates the transfer of knowledge: teaches earthquake engineering and wood. \xa0 He describes working as an engineer studying off shore structures: deep water oil platforms. It was his work at Michigan Tech that led him to testing wood structures. For one thing, he laughs, wood was a cheap material. He focused on testing shear walls in wood. (Sheer walls resist inertial loads, specifically the side-to-side forces.) \xa0 He explains that in the early 2000s, there were not many wood projects being funded, and they did not tend to be seismic projects. He says wood was thought of as a \u201cconventional product,\u201d meaning that it tended to be used in standard building projects --\xa0 although wood is used in less conventional ways In earthquake-prone regions. \xa0 Next, van de Lindt describes being part of a rather spectacular large wood project in Japan, called NEESWood. There, from 2005-2009, a group focused on building a mid-rise, six-story building \u2014 to a performance based seismic design. The shake at the E-Defense facility validated that design. \xa0 Building on such findings, a current wood project is underway at UC San Diego. The project, called Tall Wood is led by van de Lindt\u2019s former student Shiling Pei. It will validate a 10-story at full scale at UCSD. Van de Lindt says that with so many universities and industry partners, including architects, involved, it is now possible we may see large wood buildings actually implemented. This project recently completed their first round of testing at UC San Diego this past summer. \xa0 After 2009, van de Lindt was part of a project called NEESsoft. It looked at large buildings with soft stories in San Francisco, buildings with relatively unsupported first floors that served as garages or retail space. Van de Lindt says everyone knew the buildings were dangerous but that the building owners no real incentives to retrofit. The NEESsoft project developed retrofits to protect buildings \u2013 which ultimately would prevent population dislocation after an earthquake. The team tested number of retrofits, including FEMA-based retrofits and performance based retrofits, hoping to give options to building owners. Because the buildings already existed, he says, there are many constraints, but achieved the best solution. He describes collapsing a four-story building to demonstrate what would happen without retrofits. Soft-story retrofits are now mandatory and still ongoing in San Francisco.